Besides the jammers that were installed for over Rs 1 crore, other monitoring mechanisms like manual frisking and short-circuit cameras were also put in place in the jail, which is home to dreaded criminals like Aftab Ansari and Gopal Tiwari. But these have failed to deter the inmates from networking with the outside world, be it calling up their cohorts or family members.

Biswanath Chowdhury, state’s jail minister, is however, optimistic. “Look at the bright side. It is because we are running regular checks that so many cellphones have been seized. We are doing our best to tackle this menace,” he said.

To secure the jail, the state government had hired Webel Electronics Communication System, which installed six sophisticated jammers on March 31, 2006 at a cost of around Rs 20 lakh each.

Jail sources, however, said the raids showed vast areas of jail premises remained out of coverage of jammers.

“The six jammers were placed atop only a few cells. Vast areas in the jail were not covered by it. Only cell numbers 1, 2, 13, and 14 are covered by the jammers. Only one criminal is lodged in each of these cells. The hundreds of other undertrials and convicts who are in the wards are free to use cellphones. There is a gaping hole in security,” said a senior officer who was part of recent surprise raids.